Quartet 1457Q Left Ventricular (LV) Lead Investigational Device Exemption (IDE) Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Quartet 1457Q Left Ventricular (LV) Lead Investigational Device Exemption (IDE) Study (NCT02548455), a na na study. The primary outcome is Number of Patients Free From LV Lead-related Complications Through 3 Months.

2. Clinical Question

The registry frames the study as an assessment of lead safety at 3 months in a population indicated for cardiac resynchronization therapy. It does not describe a comparison with another lead, a non-device group, or usual care. Consequently, the central question is descriptive: what was observed among participants who received the Quartet 1457Q LV lead under the study conditions?

The primary endpoint is not a general measure of all health events. Its definition is limited to serious adverse device effects related to the lead. The registry describes these as events related to device use that led to specified serious consequences, including death, life-threatening illness or injury, permanent impairment, hospitalization, or intervention to prevent serious harm. It also includes specified reproductive and fetal outcomes. The registry does not report the endpoint result, so the number free from these complications cannot be stated from the record.

3. Trial Design

NCT02548455 is a completed, single-group device study sponsored by Abbott Medical Devices. The registered intervention is the Quartet 1457Q LV Lead. The registry lists 499 participants as the enrollment and identifies heart failure as the condition. The study’s stated purpose was to assess device safety at 3 months among patients indicated for cardiac resynchronization therapy.

The study began on 2015-10-27, and primary completion is recorded as 2016-08-19. The registry status is COMPLETED. Phase is listed as NA. Masking is listed as NONE, and allocation is listed as NA. A treatment description says subjects were implanted with the Quartet 1457Q LV lead. The record does not describe a parallel control group or a randomized allocation process.

This design supports description of outcomes observed in the treated group, but it does not itself establish how those outcomes compare with another device or with no implantation. Without a concurrent comparison group, differences due to patient characteristics, clinical practice, or other influences cannot be separated from outcomes associated with the device. The record does not report a protocol-level explanation for the absence of a comparator, the intended enrollment rationale, or details of the statistical analysis plan.

The primary endpoint population is described separately from overall enrollment: it includes the first 94 subjects who underwent an attempted implant and either completed a 3-month follow-up visit, withdrew, or died before that visit. This endpoint-specific description matters when interpreting the primary measure. The registry does not state how the endpoint population was selected beyond that description, nor does it report the number meeting the endpoint.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The first 94 subjects who underwent an attempted implant of the Quartet 1457Q lead and either completed a 3-month follow-up visit, withdrew from the study or died prior to the 3-month follow-up visit.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Number of Patients Free From LV Lead-related Complications Through 3 Months, measured over 3 months.

The primary endpoint is the number of participants free from LV lead-related complications through 3 months. The registry defines a complication as a Serious Adverse Device Effect related to the Quartet 1457Q lead. In general, a binary safety endpoint records whether each participant meets a specified event definition; the count free of the defined complication is the complementary way to describe that outcome.

The definition focuses on serious consequences related to use of the device. It includes events such as death, life-threatening illness or injury, permanent impairment, hospitalization, or medical or surgical intervention to prevent serious harm, as well as specified malignant tumor and fetal outcomes. Because the endpoint is limited to serious events judged related to the lead, it should not be read as a count of every adverse event or every health event occurring during follow-up.

Using a defined safety endpoint helps make the intended outcome explicit and sets a time window for assessment. The 3-month timeframe also anchors the interpretation: it is not a statement about longer-term safety. The record identifies the endpoint population and definition, but does not report the observed number of participants free from complications or the corresponding uncertainty. Therefore, the endpoint’s observed result cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The main statistical distinction in this study is between a defined endpoint and a reported endpoint result. The registry defines a binary safety outcome: whether a participant was free from a specified lead-related complication through 3 months. It also states the population used for that measure. But it does not report the outcome count. A clear endpoint definition alone does not reveal how many participants met it, and no primary rate or uncertainty estimate can be recovered from the stated definition.

What does a binary endpoint represent?

In general, a binary endpoint classifies each participant according to whether a prespecified condition occurred. The outcome can be presented as a count, a proportion, or both. The count indicates how many participants had the classification, while a proportion relates that count to a defined denominator. The denominator must correspond to the analysis population for the endpoint. Here, the registry gives the endpoint population description, but not the result count or an endpoint estimate. No proportion should therefore be inferred.

Why does the endpoint definition matter?

A safety outcome depends on which events qualify, their severity, their relationship to the device, and the period in which they are assessed. The primary definition is restricted to Serious Adverse Device Effects related to the Quartet 1457Q lead and to complications through 3 months. The record describes serious consequences covered by that definition. This differs from a general count of adverse events: not every event in a safety listing necessarily meets the primary endpoint definition. The registry does not report how individual events were assessed against the endpoint definition.

What can a confidence interval add?

In general, a confidence interval expresses the uncertainty around an estimate under a specified statistical approach. A narrow interval indicates greater precision than a wide interval, while neither interval establishes causation. For a binary endpoint, an interval can be used to describe uncertainty around an estimated proportion. The registry record does not report a confidence interval or a primary endpoint estimate, so the precision of the primary safety result cannot be evaluated from the record.

What is the role of a comparison group?

A comparison group can help distinguish outcomes associated with an intervention from outcomes that might occur without it or under another intervention. This study is registered as single-group, with allocation listed as NA. It therefore offers no randomized, concurrent comparison in the record. General statistical adjustment cannot replace information that a suitable comparison group would provide, and the registry does not report an adjusted comparative analysis. The results should be read descriptively rather than as a treatment contrast.

How should the planning assumptions be understood?

The planning illustration is described as a calculation based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Its effect to detect is expressed as a stated fraction of the observed effect. Such calculations concern hypothetical future study planning; they are not observed results and are not observed power. The stated assumptions do not establish that this trial was designed with those methods. The registry record does not report the trial’s sample-size justification or its own statistical plan.

The planning description distinguishes outcomes expressed as participants per arm from time-to-event calculations expressed as a total number of events. Those conventions are about how a planning calculation is presented, not evidence that the completed study had two arms or used a time-to-event primary analysis. The registered study remains single-group, and its primary endpoint is a count of participants with the defined safety classification. No planning result should be used to fill in the missing primary endpoint outcome.

What does over-dispersion mean in general?

For count outcomes, some statistical models assume that variability follows a specified relationship to the mean. Over-dispersion occurs when observed variability is greater than that assumption allows, and it can make standard errors too small if ignored. This is a general consideration for count modeling, not a reported feature of this study. The primary endpoint is described as a participant count with a binary classification, and the registry record does not identify a count model, an over-dispersion assessment, or a model-based analysis.

Overall, the methods information supports understanding the endpoint’s definition and the study’s single-group structure, but not reconstruction of the primary result. Details of the statistical analysis plan, including any confidence-interval method, missing-data procedure, covariate adjustment, or interim analysis, are not reported in the registry record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Treatment")
n      <- c(94)
events <- c(4)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Treatment  94  4  4.3  1.2  10.5  1.7  10.4  1.7  10.4

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and one analysis. This does not establish whether multiplicity was considered in the study’s full protocol or analysis plan. Multiplicity arises in general when several outcomes, timepoints, groups, or statistical tests are examined, because repeated testing can increase the chance of a nominally unusual result. The registry record does not report a multiplicity adjustment or a rationale for not using one. No claim about control of type I error can therefore be made from the listing alone.

The primary endpoint population is specified as the first 94 subjects who underwent an attempted implant and completed a 3-month follow-up visit, withdrew, or died before that visit. That definition includes several routes to inclusion, but the record does not describe how missing endpoint information was handled, how withdrawals were classified, or whether additional participants were excluded from the primary analysis. It also does not report a missing-data sensitivity analysis or imputation method.

In general, missing-data handling can affect a safety estimate when participants with incomplete follow-up differ from those with complete follow-up. Including withdrawal and death in the stated population definition does not, on its own, explain how their endpoint status was determined. The registry record does not state whether an event was attributed to a participant who died before the 3-month visit, or how incomplete observations were treated.

The registry does not report the primary endpoint result, so it is not possible to assess how any missingness or multiplicity decisions might have affected that result. The analysis population and outcome-handling details beyond the stated population definition are not reported in the registry record.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: lead dislodgement (4.0%), pneumothorax (1.2%), infections (1.0%), coronary sinus dissection (0.8%), cardiac tamponade (0.6%).

The safety summary reports 60 affected in the serious adverse event category among 499 at risk, and 56 affected in the other adverse event category among 499 at risk. It separately reports 27 deaths. These are distinct registry entries; the record does not establish that the deaths overlap with either affected count, so they should not be added together or interpreted as mutually exclusive categories.

The serious-event terms listed are Lead Dislodgement, 4.0%; Pneumothorax, 1.2%; Infections, 1.0%; Coronary Sinus Dissection, 0.8%; Cardiac Tamponade, 0.6%; and Excessive Bleeding, 0.4%. The percentages are reported values and should not be treated as percentages of the primary endpoint population. The registry does not specify in this summary whether each listed event was judged related to the lead.

The primary endpoint has a narrower definition than the general safety categories: it counts participants free from serious adverse device effects related to the Quartet 1457Q lead through 3 months. The safety summary does not substitute for the missing primary endpoint result. These registry figures describe reported safety information; they do not establish causation or provide a comparison with another device or treatment.

13. What the Result Does, and Does Not, Mean

The record describes a completed safety study of the Quartet 1457Q LV lead in a single-group population indicated for cardiac resynchronization therapy. It defines a primary safety endpoint focused on serious adverse device effects related to the lead through 3 months. It also reports adverse-event category counts, deaths, and selected serious-event terms with percentages. These details establish what the study set out to assess and what safety summaries appear in the registry.

The record does not report the observed primary endpoint count. It therefore does not show how many participants were free from the defined complications, nor does it provide an estimate of the endpoint’s precision. The adverse-event summaries cannot be used as a substitute for that missing result because they are not stated to represent the endpoint population or the endpoint’s device-related definition.

A single-group study can describe outcomes among those enrolled and treated, but it cannot provide a randomized comparison with another device or with no intervention. The reported safety counts do not establish that the lead caused an event, and the absence of a comparator means they do not establish how outcomes would have differed under another approach. Similarly, the absence of a primary result does not establish that no complications occurred; it means the result is not reported in the registry record.

The endpoint applies through 3 months, so it does not answer questions about longer-term outcomes. The registry also does not provide the detailed analysis plan, missing-data approach, or event-adjudication information needed to resolve further questions about how the findings were derived. The record should therefore be read as a description of study design and selected safety listings, not as a complete quantitative account of the primary endpoint or a comparative assessment.

14. Why This Trial Matters Statistically

This study illustrates why endpoint definitions and endpoint results need to be read together. The registry gives a specific definition for a lead-related serious safety outcome and identifies a 3-month assessment period. Yet the primary result itself is not reported. Without the result count, the key endpoint cannot be characterized quantitatively, even though the study is marked completed and the endpoint is clearly named.

It also illustrates the importance of distinguishing an endpoint-specific population from overall enrollment. The registry reports enrollment of 499, while the primary endpoint population is described as the first 94 subjects meeting the stated implant and follow-up, withdrawal, or death criteria. Those figures refer to different descriptions in the record; they should not be combined or treated as interchangeable. The absence of a reported endpoint result makes this distinction particularly important for interpretation.

The single-group design also sets a clear boundary on inference. Adverse-event counts can be useful descriptive information, but without a comparison group they cannot quantify a difference attributable to the lead. Nor can broad adverse-event categories be assumed to equal the narrower, device-related primary endpoint.

Statistically, the case demonstrates that a completed record can still leave important reporting gaps: the primary estimate, its uncertainty, missing-data handling, and analysis details are not reported. Recognizing those gaps prevents descriptive safety listings from being mistaken for a complete comparative or causal conclusion.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most direct limitation is that the registry record does not report the primary endpoint result. Although the outcome definition and population are stated, the number free from lead-related complications and any measure of uncertainty are absent. This prevents quantitative interpretation of the study’s primary safety question.

The study is single-group and has no registered comparator. Outcomes therefore cannot be contrasted with a concurrent control under the design described in the record. The safety summaries are descriptive and do not establish that the device caused the listed events. The record does not report an event-adjudication procedure or explain how the adverse-event categories relate to the primary endpoint’s requirement for a lead-related Serious Adverse Device Effect.

The endpoint is limited to 3 months, so it does not characterize longer-term safety. The stated primary population is the first 94 subjects meeting the described criteria, whereas overall enrollment is 499. The registry record does not explain the rationale for this endpoint-population definition or report the primary outcome for that population.

Details about missing observations, withdrawal handling, deaths in endpoint classification, confidence intervals, covariate adjustment, interim analyses, multiplicity, and the statistical analysis plan are not reported in the registry record. These gaps limit assessment of precision, potential bias, and analytical choices. The listed planning assumptions are not evidence of the trial’s own design or observed power.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Quartet 1457Q Left Ventricular (LV) Lead Investigational Device Exemption (IDE) Study — NCT02548455.
• Registry record last updated 2019-02-04; status last verified 2019-01.
• Results first posted 2018-05-08.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT02548455 is a completed, single-group study sponsored by Abbott Medical Devices, evaluating the Quartet 1457Q LV lead in patients indicated for cardiac resynchronization therapy. Enrollment is 499. The primary endpoint is the number of participants free from lead-related serious adverse device effects through 3 months, in a population described as the first 94 subjects meeting the stated criteria.

The registry reports 60 affected in the serious adverse event category among 499 at risk, 56 affected in the other adverse event category among 499 at risk, and 27 deaths. It also lists selected serious-event terms with percentages. The primary endpoint result, its precision, and detailed analysis and missing-data methods are not reported in the registry record. The single-group design does not provide a registered comparator.